Add some reason tests wrt to ppx preprocessing (#375)

Add some reason tests wrt to ppx preprocessing

test/blackbox-tests/test-cases/reason/jbuild

@@ -7,7 +7,10 @@
  ((name rlib)
   (public_name rlib)
   (preprocess
-   (per_module ((action (run ./pp/reasononlypp.exe ${<})) (cppome))))))
+   (per_module
+    ((pps (reasonppx)) (foo))
+    ((pps (reasonppx (-lint false))) (hello))
+    ((action (run ./pp/reasononlypp.exe ${<})) (cppome))))))
 
 ;; we want to make sure that .rei files are present
 (alias

test/blackbox-tests/test-cases/reason/ppx/jbuild

@@ -0,0 +1,7 @@
+(jbuild_version 1)
+
+(library
+ ((name reasonppx)
+  (wrapped false)
+  (kind ppx_rewriter)
+  (libraries (ocaml-migrate-parsetree))))

test/blackbox-tests/test-cases/reason/ppx/reasonppx.ml

@@ -0,0 +1,14 @@
+let lint = ref false
+
+let () =
+  Migrate_parsetree.Driver.register
+    ~name:"reasonppx"
+    ~args:(["-lint", Arg.Bool (fun l -> lint := l), ""])
+    Migrate_parsetree.Versions.ocaml_405
+    (fun _ _cookies ->
+       if !lint then (
+         exit 0
+       ) else (
+         Migrate_parsetree.Ast_405.shallow_identity
+       )
+    )

test/blackbox-tests/test-cases/reason/run.t

@@ -1,6 +1,7 @@
   $ $JBUILDER runtest -j1 --root .
          refmt bar.re.ml
       ocamldep pp/reasononlypp.depends.ocamldep-output
+      ocamldep ppx/reasonppx.depends.ocamldep-output
          refmt hello.re.ml
          refmt pped.re.ml
         ocamlc rlib.{cmi,cmo,cmt}
@@ -8,13 +9,21 @@
          refmt hello.re.mli
          refmt pped.re.mli
         ocamlc pp/reasononlypp.{cmi,cmo,cmt}
+        ocamlc ppx/reasonppx.{cmi,cmo,cmt}
       ocamlopt rlib.{cmx,o}
       ocamlopt pp/reasononlypp.{cmx,o}
+      ocamlopt ppx/reasonppx.{cmx,o}
       ocamlopt pp/reasononlypp.exe
+      ocamlopt ppx/reasonppx.{a,cmxa}
   reasononlypp cppome.pp.re
   reasononlypp cppome.pp.rei
+      ocamlopt .ppx/reasonppx/ppx.exe
          refmt cppome.pp.re.ml
          refmt cppome.pp.re.mli
+           ppx foo.pp.ml
+           ppx hello.re.pp.ml
+           ppx foo.re.pp.mli
+           ppx hello.re.pp.mli
       ocamldep rlib.depends.ocamldep-output
       ocamldep rlib.dependsi.ocamldep-output
         ocamlc rlib__Bar.{cmi,cmti}